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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 65 · 40 questions
TalentJR

The trick (Digits add to the 9 table): Add the digits you can see. Find the next number in the 9 table (9, 18, 27 …) above that total. The hidden digit is the difference. (Any number minus its digit sum is in the 9 table too.)

NameDateTime takenScore ___ / 40
  1. 1.28?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 52 and take away the sum of its digits. What do you get?
  3. 3.Take 55 and take away the sum of its digits. What do you get?
  4. 4.Take 11 and take away the sum of its digits. What do you get?
  5. 5.Take 31 and take away the sum of its digits. What do you get?
  6. 6.547? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.38?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.6?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.5?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.361? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.82? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?515 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 90 and take away the sum of its digits. What do you get?
  14. 14.Take 56 and take away the sum of its digits. What do you get?
  15. 15.?349 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 86 and take away the sum of its digits. What do you get?
  17. 17.801? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?422 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.26?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?781 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 96 and take away the sum of its digits. What do you get?
  22. 22.2?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.5?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 43 and take away the sum of its digits. What do you get?
  25. 25.Take 23 and take away the sum of its digits. What do you get?
  26. 26.?166 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.733? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.26?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.8?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.616? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?672 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 63 and take away the sum of its digits. What do you get?
  34. 34.51?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.54?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 37 and take away the sum of its digits. What do you get?
  37. 37.?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?471 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 92 and take away the sum of its digits. What do you get?
  40. 40.2?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 3
  2. 45
  3. 45
  4. 9
  5. 27
  6. 2
  7. 9
  8. 3
  9. 1
  10. 8
  11. 8
  12. 7
  13. 81
  14. 45
  15. 2
  16. 72
  17. 9
  18. 1
  19. 2
  20. 2
  21. 81
  22. 8
  23. 7
  24. 36
  25. 18
  26. 5
  27. 5
  28. 4
  29. 7
  30. 8
  31. 5
  32. 3
  33. 54
  34. 1
  35. 4
  36. 27
  37. 5
  38. 6
  39. 81
  40. 7

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